Found a way to get my 2.4kW pro power working with Tesla Powerwalls!

[hajalie24]

Hello all,

I recently got Tesla Powerwall 3s which are great, but on weekdays I usually dump the batteries at peak hours and I can only recharge them the next day via solar. I'm worried about outages that may occur when the battery is low and the sun isn't shining. Turns out there is a way (albeit somewhat inefficient) to integrate the truck with powerwalls!

So basically you need a "grid tie inverter" or "microinverter." These take DC input (such as from solar panels or a DC power supply) and generates an AC output that is synchronized to the "grid" (which in the event of an outage is actually my powerwalls)

There are many grid tie inverters you can buy from amazon or other websites, or alternatively you can rig up something from a high quality source like Enphase microinverters. I just went the plug and play solution from amazon (I've attached an image of the product listing so you can find your own.)

Then you need a power supply that matches the voltage range of the inverter. I got two high quality Mean Well 36v DC power supplies. It's important to get a good power supply that has "power factor compensation." I first tried a cheapo PSU without PFC from amazon and my overall efficiency was terrible, like less than 50%. from truck to house. The truck was supplying way more power than the power supply was actually drawing from the AC outlet even before the subsequent AC - DC -AC losses. I learned some new terms "apparent power" vs "real power."

Some things to note:

• Unless you already have batteries, this won't work during a power outage! They're designed to sync with the grid and would turn itself off for safety reasons if the grid is not working properly.
• My overall efficiency is not great, even with a high quality power supply. I'm losing maybe 25% - 33% from what the truck reports and the power actually going into the house. Because I only have the 2.4kW inverter I also had to find a way to current limit one of the power supplies otherwise the truck would trip.
  • The powerwall does have MPPT ports, theoretically I can skip the grid tie inverter and use those which might help with efficiency.
  • Electricity is 3x more expensive during peak hours so even with losses you still come ahead (though I'll only be using this for emergencies)
• You're essentially simulating a solar panel. Excess power will be consumed by the house first and then stored in the battery or exported to the grid (if the grid is online.)
  • This can be useful to offset your house consumption without having to disconnect power first.
  • You can also export to the grid if you're so inclined, but I don't think the utility would be happy about that and it might be considered fraud
  • If you have the 9.6 kW option, you can get better efficiency (most DC power supplies run better at 240V) and fully use the 9.6 kW! (not just the 7.2kW)

Here's a screenshot of my house vitals while I was testing this out. My house load is showing negative because I was feeding it more power than I was consuming.

Let me know if you have any questions! Fortunately any outages I've had so far have been at times when the powerwalls were charged up so I haven't had to use this system in a real world situation.. yet.

Sponsored

 

[tearitupsports]

Hello all,

I recently got Tesla Powerwall 3s which are great, but on weekdays I usually dump the batteries at peak hours and I can only recharge them the next day via solar. I'm worried about outages that may occur when the battery is low and the sun isn't shining. Turns out there is a way (albeit somewhat inefficient) to integrate the truck with powerwalls!

So basically you need a "grid tie inverter" or "microinverter." These take DC input (such as from solar panels or a DC power supply) and generates an AC output that is synchronized to the "grid" (which in the event of an outage is actually my powerwalls)

There are many grid tie inverters you can buy from amazon or other websites, or alternatively you can rig up something from a high quality source like Enphase microinverters. I just went the plug and play solution from amazon (I've attached an image of the product listing so you can find your own.)

Then you need a power supply that matches the voltage range of the inverter. I got two high quality Mean Well 36v DC power supplies. It's important to get a good power supply that has "power factor compensation." I first tried a cheapo PSU without PFC from amazon and my overall efficiency was terrible, like less than 50%. from truck to house. The truck was supplying way more power than the power supply was actually drawing from the AC outlet even before the subsequent AC - DC -AC losses. I learned some new terms "apparent power" vs "real power."

Some things to note:

• Unless you already have batteries, this won't work during a power outage! They're designed to sync with the grid and would turn itself off for safety reasons if the grid is not working properly.
• My overall efficiency is not great, even with a high quality power supply. I'm losing maybe 25% - 33% from what the truck reports and the power actually going into the house. Because I only have the 2.4kW inverter I also had to find a way to current limit one of the power supplies.
  • The powerwall does have MPPT ports, theoretically I can skip the grid tie inverter and use those which might help with efficiency.
  • Electricity is 3x more expensive during peak hours so even with losses you still come ahead (though I'll only be using this for emergencies)
• You're essentially simulating a solar panel. Excess power will be consumed by the house first and then stored in the battery or exported to the grid (if the grid is online.)
  • This can be useful to offset your house consumption without having to disconnect power first.
  • You can also export to the grid if you're so inclined, but I don't think the utility would be happy about that and it might be considered fraud
  • If you have the 9.6 kW option, you can get better efficiency (most DC power supplies run better at 240V) and fully use the 9.6 kW! (not just the 7.2kW)

Here's a screenshot of my house vitals while I was testing this out. My house load is showing negative because I was feeding it more power than I was consuming.

Let me know if you have any questions! Fortunately any outages I've had so far have been at times when the powerwalls were charged up so I haven't had to use this system in a real world situation.. yet.

I understand exactly what you are doing. Where are you connecting the micro-inverter into the home system? Just a breaker on your main (or critical loads) panel?
Wouldn't a 240V inverter be a lot better?

 

[hajalie24]

I understand exactly what you are doing. Where are you connecting the micro-inverter into the home system? Just a breaker on your main (or critical loads) panel?
Wouldn't a 240V inverter be a lot better?

It just plugs into an outlet that is backed up (my whole house is backed up by the powrwalls). I actually have two inverters that I plug into outlets on different legs, but it should still work if everything is only plugged into one leg (someone I was chatting wtih on reddit confirms that's how they do it and it works fine)

I don't know if I have seen any "plug and play" style 240V inverters, especially any that can handle thousands of watts. So I kind of like just getting two 120v inverters run independently off two power supplies, especially with my truck's 2.4kw pro power limitations.

 

[K6CCC]

Interesting concept. As you stated, not very efficient, but it works.

 

[MountainAlive]

I understand exactly what you are doing. ..

That’s good because I sure don’t

 

[NW Ontario Ford Lightning]

With a Home battery-inverter-solar set up, it is easy to feed the main solar storage battery with a "EG4 Chargeverter" (signature solar or Current connected - and others sell this unit, I have two of them.)
The Chargeverter can be set to use 120v or 240v supply (from your truck) and the chargeverter is then programed to what ever amperage you want to output (from the truck) so no danger of overloading or over heating.
The output of the Chargeverter is DC directly to the main house solar storage battery, in my case "48 volt" LFP which is 48 - 54 volts DC operating.
The beauty of this is the simplicity - no danger of backfeeding to utility or overloading anything. If the main battery reaches full charge the Chargeverter ramps down amperage to zero. You can run on a 2.4kW truck plug and move 57.6kWh in a 24 hour period for use by your home - most homes will not need 57.6kWh per 24 hours during an emergency anyway. Any peak loads from the house are handled by the main solar battery and inverter, with no affect at all on the charging from the truck.
The loses are Truck battery DC to truck AC outlet, then AC back to DC at the Chargeverter. Not too bad.

 

[Scorpio3d]

Hello all,

I recently got Tesla Powerwall 3s which are great, but on weekdays I usually dump the batteries at peak hours and I can only recharge them the next day via solar. I'm worried about outages that may occur when the battery is low and the sun isn't shining. Turns out there is a way (albeit somewhat inefficient) to integrate the truck with powerwalls!

So basically you need a "grid tie inverter" or "microinverter." These take DC input (such as from solar panels or a DC power supply) and generates an AC output that is synchronized to the "grid" (which in the event of an outage is actually my powerwalls)

There are many grid tie inverters you can buy from amazon or other websites, or alternatively you can rig up something from a high quality source like Enphase microinverters. I just went the plug and play solution from amazon (I've attached an image of the product listing so you can find your own.)

Then you need a power supply that matches the voltage range of the inverter. I got two high quality Mean Well 36v DC power supplies. It's important to get a good power supply that has "power factor compensation." I first tried a cheapo PSU without PFC from amazon and my overall efficiency was terrible, like less than 50%. from truck to house. The truck was supplying way more power than the power supply was actually drawing from the AC outlet even before the subsequent AC - DC -AC losses. I learned some new terms "apparent power" vs "real power."

Some things to note:

• Unless you already have batteries, this won't work during a power outage! They're designed to sync with the grid and would turn itself off for safety reasons if the grid is not working properly.
• My overall efficiency is not great, even with a high quality power supply. I'm losing maybe 25% - 33% from what the truck reports and the power actually going into the house. Because I only have the 2.4kW inverter I also had to find a way to current limit one of the power supplies otherwise the truck would trip.
  • The powerwall does have MPPT ports, theoretically I can skip the grid tie inverter and use those which might help with efficiency.
  • Electricity is 3x more expensive during peak hours so even with losses you still come ahead (though I'll only be using this for emergencies)
• You're essentially simulating a solar panel. Excess power will be consumed by the house first and then stored in the battery or exported to the grid (if the grid is online.)
  • This can be useful to offset your house consumption without having to disconnect power first.
  • You can also export to the grid if you're so inclined, but I don't think the utility would be happy about that and it might be considered fraud
  • If you have the 9.6 kW option, you can get better efficiency (most DC power supplies run better at 240V) and fully use the 9.6 kW! (not just the 7.2kW)

Here's a screenshot of my house vitals while I was testing this out. My house load is showing negative because I was feeding it more power than I was consuming.

Let me know if you have any questions! Fortunately any outages I've had so far have been at times when the powerwalls were charged up so I haven't had to use this system in a real world situation.. yet.

I would assume that this would void the warranty on your powerwall 3?
I am looking to add additional storage to my solar system as I have one power wall 3 but end up sending a lot of energy back to the grid for not much money but to add more power walls or expansion packs is quite expensive!

 

[hajalie24]

With a Home battery-inverter-solar set up, it is easy to feed the main solar storage battery with a "EG4 Chargeverter" (signature solar or Current connected - and others sell this unit, I have two of them.)
The Chargeverter can be set to use 120v or 240v supply (from your truck) and the chargeverter is then programed to what ever amperage you want to output (from the truck) so no danger of overloading or over heating.
The output of the Chargeverter is DC directly to the main house solar storage battery, in my case "48 volt" LFP which is 48 - 54 volts DC operating.
The beauty of this is the simplicity - no danger of backfeeding to utility or overloading anything. If the main battery reaches full charge the Chargeverter ramps down amperage to zero. You can run on a 2.4kW truck plug and move 57.6kWh in a 24 hour period for use by your home - most homes will not need 57.6kWh per 24 hours during an emergency anyway. Any peak loads from the house are handled by the main solar battery and inverter, with no affect at all on the charging from the truck.
The loses are Truck battery DC to truck AC outlet, then AC back to DC at the Chargeverter. Not too bad.

Interesting, I'm looking into it but am not sure how it would integrate with the powerwalls? Maybe if I continue to use the inverter with the DC output of the chargeverter? What were you thinking?

I would assume that this would void the warranty on your powerwall 3?
I am looking to add additional storage to my solar system as I have one power wall 3 but end up sending a lot of energy back to the grid for not much money but to add more power walls or expansion packs is quite expensive!

I see no reason why this would void the warranty, it shouldn't even leave a trace. It would be different story if you skipped the inverter and wired the DC output straight to the powerwalls.

 

[NW Ontario Ford Lightning]

The chemistry side of things: the Chargeverter can connect to the DC battery terminals and everything will just 'work'.
ie the battery charges or discharges based on net load.
How this would work with a Powerwall 3 is outside of my experience - the thing to check is how the controls and monitoring will respond, be sure the max voltage of the chargerverter is set below the max voltage limit set in the power wall.

 

[TechnoSwiss]

So.... let me get this straight, you're using AC to DC power supplies plugged into your truck to get the DC voltage to feed into your DC to AC grid-tied inverter, and back-feeding that into a regular outlet on your house? Glad that's working for you, seems like it might make more sense to figure out how to get Ford's FCSP to work with any inverter, but then you'd be dealing with 400V DC...

I'm assuming since you already have solar that you already have the appropriate hardware to prevent back-feeding the grid when it's down, but without that this setup would be both illegal and dangerous to any line workers.

 

[hajalie24]

So.... let me get this straight, you're using AC to DC power supplies plugged into your truck to get the DC voltage to feed into your DC to AC grid-tied inverter, and back-feeding that into a regular outlet on your house? Glad that's working for you, seems like it might make more sense to figure out how to get Ford's FCSP to work with any inverter, but then you'd be dealing with 400V DC...

I'm assuming since you already have solar that you already have the appropriate hardware to prevent back-feeding the grid when it's down, but without that this setup would be both illegal and dangerous to any line workers.

Yes it's very convoluted, hopefully one day non sunrun/ford proprietary V2H systems exist... I'm banking on powershare being a standard for future EVs which would be nice since it will work out of the box with powerwalls.. but we shall see

This system poses no risk to line workers with or without solar. It's "grid tied", so it won't work if the grid is down. Worst case if you don't already have existing solar you will be billed for energy exported...

In countries like the UK you're actually allowed to have a setup like without any permits up to 700w.

 

[HOTAS]

Hello all,
Let me know if you have any questions!

How\ when do you charge (and recharge) your truck ?

 

[hajalie24]

How\ when do you charge (and recharge) your truck ?

I wanted to get this working during an emergency, I don't use it day to day. But if I did at most I would use it for the 6 hours when electricity is more expensive and then I'll recharge at night. It would only lose about 10% in those 6 hours.

Also something interesting, JerryRigEverything posted this new video. Apparently Utah passed a new law and now you're allowed to backfeed the grid up to 1200W, so if anyone lives in Utah they can definitely do this even if you don't have solar

Ecoflow also has a new grid tied inverter they only sell in Utah, it's 2x as much as the no-name one from amazon (and 3x more than what you can just buy in China), but I bet it's a bit more efficient.

 

[HOTAS]

One day solar / powerwall /EV charging / home backup / grid support will be simple, easy and common.
It’s a fascinating concept and I like these imaginative Implementations

 

[HOTAS]

Years ago I though I was a genius when I hooked up an inverter to the battery on my ATV to power Halloween lights on a hayride trailer …
Gas engine powers AC alternator that powers DC battery that powers AC inverter that powers lights.

Sponsored